Removal of naphthenic acids from crude oil using amino acid ionic liquids

► Amino acid based ionic liquids can be used to remove naphthenic acids from crude oil. ► Both reactive and physical extraction reduces the total acid number. ► The reaction mechanism involves the formation of a zwitterionic species. ► The zwitterionic species can be reacted with carbonic acid to reform the ionic liquid. ► Successful multistage recycling of the ionic liquid has been demonstrated.